HAZMAT — BENEFITS OF PCR

Rapid field identification of biological threats

Lou Banks
10/14/2010 -

Hazmat, firefighters, and other first responders who have been tasked with incident scene management need reliable information available to them in a timely manner in order to effectively manage incident response. Perceived biological attacks, such as the frequent white powder attack are no different. These white powder attacks usually consist of a victim receiving a threatening letter through the mail that contains a white powder alleged to be Anthrax or some other harmful biological agent. Unlike victims of a chemical or explosive attack where the attack is obvious from an obnoxious odor, burning sensation, or explosion, victims of such a biological attack will be unaware they have been infected until symptoms manifest hours or days later. And during this incubation period, the attack can spread exponentially as contagious victims contact others and unknowingly spread the deadly pathogen.

Time required to identify white powder threats has a cost — psychologically and financially. While waiting for the threat to be substantiated and identified, potential victims anxiously agonize whether they have been exposed to a deadly pathogen and businesses suffer financially as buildings are closed and productivity ceases. Response time following traditional SOPs, where a sample is sent to a local LRN lab for identification, is also handicapped since a majority of white powder attacks are hoaxes that contain harmless material such as sheetrock dust or infant formula.

The high rate of false alarms has led many LRN labs to institute more stringent criteria for accepting white powder attack samples, which has led these samples to slip in priority causing a significant response delay. Therefore, it is critical for first responders to be outfitted with validated, reliable field BioDetection equipment to obtain critical information themselves that allows them to quickly mobilize the appropriate response and minimize casualties in the event of a true attack.

BioDetection Technologies

Currently, several different technologies are utilized by responders to screen samples in the field and each has its benefits and limitations. Many SOPs realize that these technologies can complement each other and therefore require positive detection on multiple field screening methods before initiating a response. Non-specific detection methodologies will distinguish a substance as being chemical, explosive or biological in nature. However, they cannot provide specific identification of a biological substance and determine if it is harmful.

Examples include the BioCheck® Powder Screening Kit (20/20 BioResponse) which relies on a chemical reaction to identify the presence of protein and HazMatID™ (Smiths Detection) which employs FT-IR technology to identify an infrared spectrum signature. Antibody based hand-held assays (HHAs) are very popular. Examples include BioThreat Alert™ (Tetracore), Bio-Detect™ (Alexeter Technologies), and RAMP®(Response Biomedical Corp). These low-cost wicking assays rely on a molecular bonding reaction between an antibody and antigen coupled with a fluorescent or visual reporting mechanism.

HHAs can identify biological pathogens at the species level in 15 minutes, however, they have a history of high false-positive rates so results are often disputed and require a positive result using another method before initiating a response.

Recently, PCR based tests have gained popularity as a field-based assessment method for detecting and identifying biological threats. This is the same PCR technology used in LRN labs to identify biological threats.

PCR-based BioDetection

PCR-based assays have been widely utilized in laboratory settings since the 1990s for forensic applications and disease detection, as well as many other research purposes. This highly sensitive and specific molecular procedure amplifies specific regions of DNA to levels that can be detected. For BioThreat detection, assays are designed to amplify regions of DNA that are unique to the pathogen being tested. Fluorescence identifiers are integrated into these reactions to provide visual detection. If the suspected pathogen is present then DNA amplification occurs along with an increase in fluorescence which results in a positive result. However, to run a PCR reaction in the lab requires the use of delicate instruments and advanced training, along with extensive sample preparation — limitations that do not lend well to field use.

Recent innovations in PCR instrumentation and chemistry have allowed PCR to migrate to the field to be operated by users without advanced scientific training, which has made PCR a tool of choice for frontline responders. Idaho Technology, working with the U.S. Air Force, produced the first ruggedized, field-usable PCR instrument, R.A.P.I.D.®, in 1999. This instrument designed for identifying biowarfare agents weighs 50 pounds and is carried in a backpack to be used in a mobile lab setting with AC power.

Some degree of scientific training is still required to operate the R.A.P.I.D. since streamlined sample preparation is required. Idaho Technology’s newest generation field PCR instrument, RAZOR™EX, was co-developed with the United States Department of Defense (DOD) and lends itself better to field use by operators with minimal scientific training.

The RAZOR EX weighs 11 pounds and can be hand-carried. It runs off battery power and utilizes freeze-dried reagents, making it a true field instrument. Ease-of-use was central in the design with a simple dilution step for sample prep and instrument based wizards to guide users through the steps of loading the sample pouch to running the instrument and finishing with automated data analysis. A single unknown sample can be tested for up to 10 different bioterrorism pathogens simultaneously in 30 minutes.

Smiths Detection offers BioSeeq™ PLUS, a hand-held instrument which employs Late PCR Technology to identify biological threats. It can run up to six simultaneous assays and gives high-confidence results in 65 minutes. Other prototype PCR instruments are also making their way into the Biological Detection Market which shows that PCR is quickly becoming a widely accepted technology for detecting and identifying biological threats in the field and can provide first responders with the reliable information that they need.

Field testing is necessary since it provides rapid, critical information required by first responders to properly respond to threats and most importantly save lives. However, authorities have been reluctant to recognize results from field screening procedures because past history has shown field instruments to lack the required sensitivity, to be not as reliable as claimed by the manufacturers, and responders not adequately trained to accurately interpret scientific results. Conversely, recent innovations have created easy-to-use field PCR equipment that provide sensitive and reliable field testing results of biological threats and has evolved to give responders the essential tool to rapidly detect and respond to a biological threat.

Lou Banks is Marketing Manager — Biodefense at Idaho Technology. He can be reached at 801-736-6354 x487 or e-mail [email protected].